> > Correct. Therefore the set of antidiagonals appears to be uncountable> > = unlistable. But it is countable.>> I don't see why you say it appears to be uncountable. (See below)>

> > The set of antidiagonals that can be constructed (by a given> > substitution rule) from an infinite sequence of lists.>> Ah, OK.>> So we have (L0, L1, L2, ...), and corresponding to each Ln we have an> antidiagonal An. So we have a sequence (A0, A1, A2, ...).>> But (A0, A1, A2, ...) is obviously countable. Above you say it's "certainly> not countable", but it is.

The set is certainly countable. But it cannot be written as a listbecause the antidiagonal of the supposed list would belong to the setbut not to the list. Therefore it is not countable.